1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a reflective liquid crystal display device having an uneven reflective layer and a fabricating method thereof.
2. Discussion of the Related Art
Generally, reflective liquid crystal display (LCD) devices use ambient light while transmissive LCD devices use light from a backlight unit. Accordingly, reflective LCD devices are more compact than transmissive LCD devices. However, because light is not effectively controlled in reflective LCD devices, brightness degrades as the viewing angle increases due to decreasing reflectance. To overcome this problem, an uneven reflective layer is formed. Because light is scattered at the uneven reflective layer, the viewing angle and brightness are improved.
FIG. 1 is a schematic plane view of an array substrate of a reflective liquid crystal display device according to the related art. As shown in FIG. 1, a gate line 12 is formed on a substrate 10 and a data line 26 crosses the gate line 12. A pixel region “P” is defined by the intersection of the gate line 12 and the data line 26. A thin film transistor (TFT) “T” including a gate electrode 14, an active layer 18 and source and drain electrode 22 and 24 is connected to the gate line 12 and the data line 26. A metal pattern 27 with an island shape is formed over the gate line 12. A storage capacitor “Cst” using a portion of the gate line 12 as a first electrode and the metal pattern 27 as a second electrode is formed at one side of the pixel region “P.” A reflective electrode 32 contacting the drain electrode 24 is formed in the pixel region “P.” The reflective electrode 32 has unevenness “A.” To form the unevenness “A” of the reflective electrode 32, an insulating layer (not shown) may be formed to have a first unevenness on its surface and the reflective electrode 32 may be formed on the insulating layer to have a second unevenness corresponding to the first unevenness.
FIG. 2 is a schematic cross-sectional view, which is taken along a line “II—II” of FIG. 1, showing a reflective liquid crystal display device according to the related art. As shown in FIG. 2, a reflective LCD device 9 includes first and second substrates 10 and 30 facing and spaced apart from each other, and a liquid crystal layer 40 interposed therebetween. The first substrate 10 includes a pixel region “P” and a TFT “T” is formed at a portion adjacent to the pixel region “P.” The TFT “T” includes a gate electrode 14, an active layer 18, an ohmic contact layer 20, a source electrode 22, and a drain electrode 24. The active layer 18 is formed over the gate electrode 14 and the ohmic contact layer 20 is formed on the active layer 18. The source and drain electrodes 22 and 24 contact the ohmic contact layer 20. Even though not shown in FIG. 2, a gate line 12 (of FIG. 1) connected to the gate electrode 14 intersects a data line 26 connected to the source electrode 22 to define the pixel region “P.”
A reflective electrode 32 connected to the drain electrode 24 is formed in the pixel region “P.” The reflective electrode 32 includes unevenness “A.” When ambient light meets the unevenness “A” of the reflective electrode 32, the ambient light does not reflect back along the direction of the ambient light but scatters in various directions. Accordingly, the viewing angle and brightness of the display are improved. The unevenness of the reflective electrode 32 may be obtained by forming a passivation layer 28 to have a first unevenness on its surface and forming the reflective electrode 32 on the passivation layer 28 to have a second unevenness corresponding to the first unevenness. The first unevenness may be formed by patterning an additional photosensitive organic layer on the passivation layer 28.
A color filter layer 34 including red, green, and blue sub-color filters 34a, 34b, and 34c is formed on the second substrate 30. Each of the red, green, and blue sub-color filters 34a, 34b, and 34c corresponds to the pixel region “P.” A black matrix 32 is formed between the adjacent sub-color filters, and a common electrode 36 is formed on the color filter layer 34.
However, because the passivation layer 28 under the reflective electrode 32 is formed of an organic material, adhesion between the passivation layer 28 and the reflective electrode 32 is poor. For example, the reflective electrode 32 may be lifted from the passivation layer 28. The lifting of the reflective electrode 32 may cause a distortion of an electric field between the reflective electrode 32 and the common electrode 36 and thus result in a degradation of display quality.